The present invention disclosed herein relates to a terahertz wave apparatus, and more particularly, to a wavelength tuning terahertz wave apparatus.
In relation to a terahertz wave band (e.g., a range of about 0.1 THz to about 3 THz), terahertz waves may penetrate nonmetal and nonpolar substances. In addition, resonant frequencies of various molecules are distributed in the terahertz wave band. Therefore, since those molecules are detected in real time through a non-destructive, non-opening, and non-contact method, they may be used as a new conceptual analysis technology in various fields such as medical service, medicine, agriculture, food, environmental measurement, bio, and advanced material evaluation. Accordingly, terahertz wave technologies rapidly expand into various kinds of applications. Since terahertz waves have almost no effect on human bodies due to a very low energy level of several meV, as essential core technology for realizing human-oriented ubiquitous society, demands on terahertz waves have been drastically increased. However, terahertz wave technologies for satisfying real-time, portable, and economical properties have not been developed yet.
Examples of currently-used terahertz continuous wave generating methods include a frequency multiplying method, a backward wave emitting method, a photo-mixing method, a CO2 pumped gas laser method, a quantum cascade laser method, and a free electron laser method. Many studies are being conducted to develop a terahertz wave source operating in a frequency band of about 0.1 THz to about 10 THz, a so-called terahertz gap band. However, small-size, non-cooling, high-performance wave source technology necessary for commercialization has not been developed maturely. In addition, technology for tuning terahertz waves in a wide frequency band has not been developed also. If terahertz waves are tuning at fast speed in a wide frequency band, it is possible to monitor a variety of physical phenomena in real time within a terahertz wave band.
The most extensively used terahertz wave apparatus until recently is a time domain spectroscopy apparatus that generates and detects terahertz pulse waves by projecting a femtosecond level ultra-short laser pulse on a photoconductive antenna based on a semiconductor with a high-speed response time. A terahertz wave apparatus including the femtosecond level ultra-short pulse laser and the photoconductive antenna has advantages such as a high signal-to-noise ratio (SNR) but also has limitations in developing it into a measuring instrument in aspects of price and size because it requires a femtosecond level pulse laser and a very precise optical system.